Has anyone had a SERVICE FUEL SYSTEM code come on the dash and if so how can I fix it. I just stopped to top up the gas tank and after driving I noticed the gas gauge showing empty and then it went to full and a couple minutes later back to empty.So I pulled over and removed the gas cap and tighten it back up and drove off and it came back again I repeated the same over and over with the same results.Any suggestions would be welcome.

 

Yes! I have an '05 MN6 Coupe.

The exact same thing happened to me two weeks ago. I was just finishing up my original tankful from CARMAX. I stopped at my local EXXON station to fill up for the first time since picking up the car.

I had read previous posts about the problems with "Topping Off", so when it clicked I removed the nozzel and left the station. At first my fuel guage read about 3/4 full and gradually, within about 30 seconds, pegged over to full.

About a mile down the road I noticed the "Service Fuel System" message and noticed that my gauge needle had pegged over to empty.

After a few more miles, the message went away and my needle pegged back over to full. It flipped/flopped a couple more times before I got home (about 15 miles from the station), but ended with the message showing and the fuel gauge indicating empty.

When I went out to drive it the following weekend (last weekend), the message was gone and the fuel gauge was indicating full, but the "Check Engine Light" came on and has continued to stay on through my weekend drive yesterday. Fuel gauge still operating normally and no "Service Fuel System" messages since the first incident two weeks ago.

I decided to put "ONSTAR" to work and asked them for a on the spot diagnostic check to see exactly what was causing the "Check Engine Light" to remain lit.

They came back and said that the CEL was due to some malfunction of the fuel gauge and that it wasn't something that required immediate attention, especially if the gauge appeared to working normally.

I also tried fiddling around with the gas cap, but it didn't affect the CEL at all, its still lit.

Do a forum search, there are several extensive threads regarding this problem, it's well documented and discussed.

Let us know if you are able to get it resolved.

DH

 

Your fuel gauge sender in the fuel tank is contaminated (typically, high sulfur fuel has been used in the car). Sometimes, adding a couple of bottles of Techron additive to the fuel will clean the sender sufficiently to allow it to work properly. GM also has a reflash that is basically a work around for a contaminated sender. If neither of those work, then they'll need to drop the tanks and change the sender cards.

 

Thanks so much for your replys you guys are very helpfull.THANKS GARY

 

Try doing a search on this, you will find more info than you can read. I'm on my second bout of this, apparently GM hasn't figured out yet how to make a fuel gauge work. Hmmm eddie